The field of the invention generally relates to the use of illumination in bar code readers and, more specifically, to controlling the intensity of the light emitting diodes (LEDs) that are used to illuminate a bar code target area.
Automatic data storage systems exist for use with computers and other systems. These systems typically consist of a storage area for storing data cartridges or other media and one or more drives for reading data from, or writing data to, the data cartridges. The data cartridges may be stored in one or more storage racks or xe2x80x9cmagazines.xe2x80x9d Each of the magazines is capable of holding a plurality of data cartridges. When a host computer needs to read data from, or write data to, a particular data cartridge, a cartridge access device is used to remove the desired data cartridge from its storage magazine, carry the cartridge to the appropriate drive, and insert the cartridge into the appropriate read/write drive. When the drive has completed its read/write operation or other processing, the cartridge access device is used to remove the tape cartridge from the drive and to return the cartridge to the appropriate magazine storage area.
Such data storage systems are often referred to as xe2x80x9cjukeboxxe2x80x9d data storage systems. These jukebox systems can be sized according to the host system""s requirements. For example, jukebox storage systems may range from small systems that have a single drive and less than ten data cartridges to systems having more than ten drives and more than a hundred data cartridges. The jukebox storage system has a control system that controls the cartridge access device that moves the data cartridges between the storage magazines and the read/write drives. The cartridge access device may include a cartridge engaging assembly or xe2x80x9cpickerxe2x80x9d that is used to engage the cartridge and to move the cartridge between the storage magazine and the drive. The picker may be used to withdraw and replace the cartridge from the magazine and to insert and remove the cartridge from the drive. Such a system is disclosed in U.S. Pat. No. 6,160,786, entitled xe2x80x9cCartridge Engaging Assembly With Rack Drive Thumb Actuator Systemxe2x80x9d, the disclosure of which is hereby incorporated herein by reference.
A need exists for the cartridge engaging assembly or picker to identify specific data cartridges in the data storage system to ensure that the picker engages the correct cartridge. This may be accomplished by having the picker read a bar code label or other label that is affixed to the data cartridge. The data storage rack or magazine may consist of a number of slots for holding individual data cartridges. At times a magazine slot may be empty, such as when a data cartridge has already been moved to a read/write drive. Accordingly, there is also a need for the picker to detect when no data cartridge is present in a magazine slot.
The invention is directed to a method and apparatus for using light sources, such as LEDs, to illuminate target areas. At least one embodiment of the invention provides a system for illuminating target areas using multiple light sources, wherein the system comprises a first light source configured to illuminate a first target area. The system further comprises a second light source configured to illuminate a second target area, wherein the second target area is located more distant from the second light source compared to the distance from the second light source to the first target area. According to at least one embodiment, the illumination from the first light source and the illumination from the second light source overlaps on the first target area, and the intensities of the first and second light source are adjusted to provide a relatively balanced illumination of the first target area.
According to another embodiment of the present invention, a system for illuminating target areas is provided, which comprises a first light emitting array positioned to illuminate a primary target area. The system further comprises a second light emitting array positioned to illuminate a alternate target area, wherein the distance from the second array to the alternate target area is greater than the distance from the second array to the primary target area. The system also includes an illuminator lens positioned in relation to the second array so that light from the second array is directed across the primary target area to the alternate target area. According to such embodiment, the intensities of individual elements within the first and second arrays are adjusted to provide a relatively even distribution of light over the primary target area.
According to yet other embodiments of the present invention, a method for illuminating target areas using a plurality of light sources is disclosed. In at least one embodiment, such a method comprises illuminating a first target area with a first light source array. The method further comprises directing light from a second light source array toward a second target area, wherein the light from the second light source array passes over at least part of the first target area, thereby causing the first target area to be illuminated by both the first and second light source arrays. Further, the method includes adjusting the illumination levels of individual light sources within the first and second arrays so that the illumination over the first target area is relatively even.